ETH Address - upper and lower characters does NOT matter?

Hello.I have printed several ETH paper wallets via https://www.myetherwallet.com/ yesterday and have noticed that sometimes it gives me ETH Address with upper and lower characters and sometimes - only with lower characters, e.g.:

0xA0100A27374bAedd24504B9c02b8356Fa1dE54c8 << in browser I see this0xa0100a27374baedd24504b9c02b8356fa1de54c8 << this one I see on "Print" pages

Well... as I understand "A" and "a" has different code in binary form...An I wrong? Bitcoin addresses also does not recognize my address if I change "A" to "a". ETH seems like it treats the same "A" and "a" in address line, but I can't understand the logic - WHY.

Comments

Ethereum wallet addresses are in hex [0-9A-F]*. While the address itself is case-insensitive (A is the same as a to the network), the case sensitivity is used as a (optional) checksum. It was built as an after-thought to an addressing scheme that lacked basic checksum validation.